There are many restaurants offering takeout and caterers in Yerushalayim with Badatz hashgacha . The problem is that most but not all of them remain open for Peseach. I can’t post the link but if you search online your will find an uppdated list and contact information for restaurants and caterers under Badatz Mehadrin (R’ Rubin). You will have to select several close to your location and contact them to see if they will be open for Pesach. Perhaps if you post the neighborhood where you will be staying, some of the local CR readers might have a recommendation.